s0055_jump_game

55. Jump Game

Medium

You are given an integer array nums. You are initially positioned at the array's first index, and each element in the array represents your maximum jump length at that position.

Return true if you can reach the last index, or false otherwise.

Example 1:

Input: nums = [2,3,1,1,4]

Output: true

Explanation: Jump 1 step from index 0 to 1, then 3 steps to the last index.

Example 2:

Input: nums = [3,2,1,0,4]

Output: false

Explanation: You will always arrive at index 3 no matter what. Its maximum jump length is 0, which makes it impossible to reach the last index.

Constraints:

• 1 <= nums.length <= 104
• 0 <= nums[i] <= 105

Solution

class Solution {
    /**
     * @param Integer[] $nums
     * @return Boolean
     */
    public function canJump($nums) {
        $sz = count($nums);
        $tmp = 1;
        for ($i = 0; $i < $sz; $i++) {
            $tmp--;
            if ($tmp < 0) {
                return false;
            }
            $tmp = max($tmp, $nums[$i]);
            if ($i + $tmp >= $sz - 1) {
                return true;
            }
        }
        return true;
    }
}